The present invention relates to a miniature circuit-breaker which works with at least one thermal trip element. This is also understood to include other circuit-breakers which work with at least one thermal trip element. These types of miniature circuit-breakers are found on the market in many different kinds of designs. As a rule, they work with a breaker mechanism, which can usually be released by a magnetic trip element and by a thermal trip element to allow the switching contacts to open. The electric arc that is struck is usually extinguished in an arcing chamber.